One thing I have noticed studying web traffic logs is that daily human behavior at scale resembles a sine wave:

Over the years, my mind’s eye has constructed an image of the daily ebb and flow of web traffic resembling the ebb and flow of ocean tides. I’ve learned that code tends to break at the “high tide”, and the best time to do site maintenance is at “low tide”.

So why does human behavior at scale look like a sine wave? It’s because of our daily cycles of waking and sleeping. In other words, we have a 24 hour cycle because of circadian rhythms, which occur because of the cycles of darkness and light caused by planetary movement.